Solution for Coordination Compounds (CBSE Class 12 Chemistry)
(a) IUPAC Name and Geometrical Isomer
- Step 1 (IUPAC Nomenclature): [0.5 Mark]
Identify the ligands and central metal oxidation state. The complex is $[Pt(en)_2Cl_2]^{2+}$.
Oxidation state of Pt: $x + 2(0) + 2(-1) = +2 \implies x = +4$.
IUPAC Name: Dichloridobis(ethane-1,2-diamine)platinum(IV) ion.
- Step 2 (Geometrical Isomerism): [0.5 Mark]
The optically inactive isomer is the trans-isomer, as it possesses a plane of symmetry.
- Step 3 (Structure): [1.0 Mark]
Drawing the trans-isomer (Cl atoms at 180°):
$$ \begin{array}{c} \text{Cl} \\ | \\ \text{en} - \text{Pt} - \text{en} \\ | \\ \text{Cl} \end{array} $$
OR (b) Formula and Linkage Isomer
- Step 1 (Formula Construction): [1.0 Mark]
Pentaamminecarbonatocobalt(III) chloride:
Pentaammine = $(NH_3)_5$; Carbonato = $(CO_3)^{2-}$; Cobalt(III) = $Co^{3+}$; Chloride = $Cl^-$.
Balancing charges: $[Co(NH_3)_5(CO_3)]Cl$. Since $Co$ is $+3$ and $CO_3$ is $-2$, the complex ion is $+1$, requiring one $Cl^-$.
Final Formula: $[Co(NH_3)_5(CO_3)]Cl$.
- Step 2 (Linkage Isomerism): [1.0 Mark]
The complex is $[Co(NH_3)_5(NO_2)]Cl_2$. The linkage isomer involves the ambidentate ligand $NO_2^-$ bonding through oxygen ($ONO^-$).
IUPAC Name: Pentaamminenitrito-O-cobalt(III) chloride.